Process for the preparation of silica for glass batches



Patented Feb. 1, 1938 UNITED STATES PROCESS FOR THE PREPARATION OF SIL- ICA FOR GLASS BATCHES Harrison 1'. Hood, Corning, N. Y., assignor to Corning Glass Works, Corning, N. Y., a corrotation of New York Application March 23, 1936, Serial No. 70,545

No Drawing.

5 Claims. (Cl. 209-1Q6) This invention relates to the preparation of silica for glass batches and has for its object the removal of iron impurities therefrom.

In my prior application Serial Number 732,729, flied June 27, 1934, of which this application is a continuation in part, I have disclosed and claimed a method of purifying silica for use in glass batches which comprises introducing the finely pulverized silica into a water solution containing a mineral acid in a flotation cell or cells, adding thereto a flotation oil comprising a sulfur derivative of cresol and agitating the mixture to float off iron impurities. By means of the method there disclosed, I am able to decrease the iron content of the pulverized silica, including metallic iron as well as iron bearing compounds, to the unusually low value of .004% calculated as F8203. This result is due largely to the cresol derivative which is capable 'of producing a substantially quantitative separation of the iron when usedas a flotation reagent in the above process. A jig or concentration table or magnetic separator may also be employed in conjunction with the flotation apparatus and preferably preliminary thereto whereby the iron content of the silica may be reduced still further to the value of .001% calculated as F9203.

The present invention comprises the method of treating silica by flotation in which flotation reagents comprising derivatives of naphthalene such as, for example, alpha'naphthylamine hydrochloride; beta naphthylamine hydrochloride; naphthalic acid; l-naphthaiamine 4-sulfonic acid; l-naphthylamine 4,8'-disulfonlc acid; 2-naphthylamine 4,8-disulfonic acid; l-naphthylamine 3,6,8-trisulfonlc acid and alpha naphthyl isocyanate, are used in lieu of the sulfur derivative of cresol.

I have discovered that the naphthalene demineral acid, preferably sulfuric acid or hydrochlorlc acid, and the mixture is introduced into the flotation apparatus where it is agitated to keep the silica in suspension. Heat is preferably applied by passing into the ,mixture sufficient steam to maintain the temperature at about 50 C.

To the agitated mixture are added the flotation reagents which in the present instance comprise preferably pine oil, in the amount of about one liquid ounce per hundred pounds .of silica, and a naphthalene derivative in the amount of about one ounce avoirdupois per hundred pounds of silica. For continuous operation these reagents are added continuously in this ratio to the silica and water mixture as it enters the apparatus. A concentration table or jig may also be employed if desired and should preferably be employedbefore the flotation process.

After thus being purified, the silica is washed and dried, after which it may be weighed and mixed into the glass batch in the customary manner.

I claim:

1. The method of preparing silica for use in v glass batches, which includes introducing the silica into an acid solution, adding thereto a flotation reagent including a naphthylamine compound, agitating the solution in a flotation apparatus to float off the iron impurities, and I tion reagent comprising naphthylamine hydrochloride, agitating the solution in a flotation apparatus to remove. the r-sidual iron impurities which remain after the concentration treatment,

and drying the silica.

4. The method of preparing silica for use in glass batches, which? includes pulverizing the silica, washing the silica on a concentration table to remove iron impurities therefrom, introducing the silica into an acid solution containing a flotation reagent comprisingpine oil and naphthylamine hydrochloride, agitating the solution in a flotation apparatus to remove the residual iron impurities which remain after the concentration treatment, and drying the silica.

5. The method of preparing silica for use in glass batches, which includes introducing the silica into an acid solution, adding thereto a flotation reagent including a naphthalene derivative of the group consisting of alpha naphthyl-.

amine hydrochloride, beta naphthylamine hydrochloride, naphthalic acid, l-naphthylamine 4-sulfonic acid, l-naphthylamine 4,8-disulfonic acid, 2-naphthylamine 4,8-disulfonic acid, l-naphthylamine 3,6,8-trisulfonic acid and alpha naphthyl isocyanate, agitating the solution in a flotation apparatus to float of! the iron impurities, and drying the silica.

'HARRrsoN P. noon. in 

